Water treatment system and method

ABSTRACT

A water treatment system provides treated or softened water to a point of use by removing a portion of any hardness-causing species contained in water from a point-of-entry coming from a water source, such as municipal water, well water, brackish water and water containing foulants. The water treatment system typically treats the water containing at least some undesirable species before delivering the treated water to a point of use. The water treatment system has a controller for adjusting or regulating at least one operating parameter of the treatment system or a component of the water treatment system to optimize the operation and performance of the system or components of the system. A flow regulator regulates a waste stream flow to drain and can be operated to recirculate fluid through electrode or concentrating compartments of an electrochemical device and can opened and closed intermittently according to a predetermined schedule or based on an operating parameter of the water treatment system. The flow regulator can also be charged so that ionic species can be generated in the surrounding fluid, which, in turn, can lower the pH of the surrounding fluid.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a system and method fortreating a fluid and, more particularly, to a water treatment systemincorporating an electrochemical device, a reservoir system and a rejectflow regulator and methods thereof for delivering treated water to apoint of use.

2. Description of Related Art

Water that contains hardness species such as calcium and magnesium maybe undesirable for some uses in industrial, commercial and householdapplications. The typical guidelines for a classification of waterhardness are: zero to 60 milligrams per liter (mg/l) as calciumcarbonate is classified as soft; 61 to 120 mg/l as moderately hard; 121to 180 mg/l as hard; and more than 180 mg/l as very hard.

Hard water can be softened or treated by removing the hardness ionspecies. Examples of systems that remove such species include those thatuse ion exchange beds. In such systems, the hardness ions becomeionically bound to oppositely charged ionic species that are mixed onthe surface of the ion exchange resin. The ion exchange resin eventuallybecomes saturated with ionically bound hardness ion species and must beregenerated. Regeneration typically involves replacing the boundhardness species with more soluble ionic species, such as sodiumchloride. The hardness species bound on the ion exchange resin arereplaced by the sodium ions and the ion exchange resins are ready againfor a subsequent water softening step.

Other systems have been disclosed. For example, Dosch, in U.S. Pat. No.3,148,687 teaches a washing machine including a water softeningarrangement using ion exchange resins. Similarly, Gadini et al., inInternational Application Publication No. WO00/64325, disclose ahousehold appliance using water with an improved device for reducing thewater hardness. Gadini et al. teach of a household appliance having acontrol system, a water supply system from an external source and asoftening system with an electrochemical cell.

Electrodeionization (EDI) is one process that may be used to softenwater. EDI is a process that removes ionizable species from liquidsusing electrically active media and an electrical potential to influenceion transport. The electrically active media may function to alternatelycollect and discharge ionizable species, or to facilitate the transportof ions continuously by ionic or electronic substitution mechanisms. EDIdevices can include media having permanent or temporary charge. Suchdevices can cause electrochemical reactions designed to achieve orenhance performance. These devices also include electrically activemembranes such as semi-permeable ion exchange or bipolar membranes.

Continuous electrodeionization (CEDI) is a process wherein the primarysizing parameter is the transport through the media, not the ioniccapacity of the media. A typical CEDI device includes semi-permeableanion and cation exchange membranes. The spaces between the membranesare configured to create liquid flow compartments with inlets andoutlets. A transverse DC electrical field is imposed by an externalpower source using electrodes at the bounds of the membranes andcompartments. Often, electrode compartments are provided so thatreaction product from the electrodes can be separated from the otherflow compartments. Upon imposition of the electric field, ions in theliquid are attracted to their respective counter-electrodes. Anion-depleting (depleting) compartment, bounded by the electroactiveanion permeable membrane and cation membrane, typically become ionicallydepleted and an adjoining ion-concentrating (concentrating)compartments, bounded by the electroactive cation permeable membrane andthe electroactive anion membrane, typically become ionicallyconcentrated. The volume within the depleting compartments and, in somecases, within the concentrating compartments, also includes electricallyactive media. In CEDI devices, the media may include intimately mixedanion and cation exchange resins. The ion-exchange media typicallyenhances the transport of ions within the compartments and mayparticipate as a substrate for controlled electrochemical reactions.Electrodeionization devices have been described by, for example,Giuffrida et al. in U.S. Pat. Nos. 4,632,745, 4,925,541 and 5,211,823,by Ganzi in U.S. Pat. Nos. 5,259,936 and 5,316,637, by Oren et al. inU.S. Pat. No. 5,154,809 and by Kedem in U.S. Pat. No. 5,240,579.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a method of treatingwater. The method can comprise introducing water into an electrochemicaldevice to produce treated water and a concentrate stream, recirculatingat least a portion of the concentrate stream in a concentratingcompartment of the electrochemical device, and discharging apredetermined portion of the concentrate stream according to apredetermined discharge schedule.

In accordance with one or more embodiments, the present inventionprovides an electrochemical device comprising a concentratingcompartment and a positively-charged flow regulator positioneddownstream of the concentrating compartment.

In accordance with one or more embodiments, the present inventionprovides a method of facilitating water treatment. The method cancomprise providing an electrochemical device comprising a concentratingcompartment and a flow regulator positioned downstream of theconcentrating compartment. The flow regulator constructed and arrangedto have a positive charge during operation of the electrochemicaldevice.

In accordance with one or more embodiments, the present inventionprovides a method of treating water. The method can comprise introducingwater into an electrochemical device to produce treated water, storingat least a portion of the treated water, ceasing production of thetreated water, and replacing any fluid in the electrochemical devicewith the treated water.

In accordance with one or more embodiments, the present inventionprovides a system comprising a point-of-entry, an electrochemical devicecomprising a depleting compartment and a concentrating compartmentfluidly connected to the point-of-entry, a positively-charged flowregulator fluidly connected downstream of the concentrating compartment,a reservoir system fluidly connected to the depleting compartment, and apoint of use fluidly connected to the reservoir system.

In accordance with one or more embodiments, the present inventionprovides an electrodeionization device comprising a concentratingcompartment and a flow regulator regulated by a controller according toa predetermined discharge schedule and fluidly connected downstream ofthe concentrating compartment for regulating a flow of a waste stream toa drain.

In accordance with one or more embodiments, the present inventionprovides a method of softening water. The method can compriseintroducing water to a depleting compartment of an electrochemicaldevice to produce softened water, recirculating a concentrating streamin a concentrating compartment of the electrochemical device, andchanging a pH of the concentrating stream proximate a flow regulator.

In accordance with one or more embodiments, the present inventionprovides an electrodeionization device comprising a concentratingcompartment with a flowing waste stream and a diaphragm valve forregulating a portion of the flowing waste stream from the concentratingcompartment to a drain.

In accordance with one or more embodiments, the present inventionprovides an electrodeionization device comprising a concentratingcompartment with a flowing waste stream and means for discharging aportion of the waste stream from the concentrating compartment to adrain according to a predetermined schedule.

In accordance with one or more embodiments, the present inventionprovides an electrochemical device comprising a concentratingcompartment with a waste system, means for discharging the waste streamto a drain, and means for applying a positive charge on the means fordischarging the waste stream.

In accordance with one or more embodiments, the present inventionprovides a method of facilitating fluid treatment. The method cancomprise providing a fluid treatment system comprising anelectrochemical device comprising a depleting compartment and a flowregulator regulated by a controller according to a predetermineddischarge schedule and fluidly connected downstream of the concentratingcompartment for regulating a flow of a waste stream to a drain.

Other advantages, novel features and objects of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings, which areschematic and are not intended to be drawn to scale. In the figures,each identical or substantially similar component that is illustrated invarious figures is represented by a single numeral or notation. Forpurposes of clarity, not every component is labeled in every figure, noris every component of each embodiment of the invention shown whereillustration is not necessary to allow those of ordinary skill in theart to understand the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred, non-limiting embodiments of the present invention will bedescribed by way of example and with reference to the accompanyingdrawings, in which:

FIG. 1 is a process flow diagram of a water treatment system showing areservoir system having a set of sensors and an electrodeionizationdevice in accordance with one or more embodiments of the invention;

FIG. 2 is a schematic, sectional view through a typicalelectrodeionization device, illustrating the fluid and ion flowdirections through depleting and concentrating compartments inaccordance with one or more embodiments of the invention;

FIG. 3 is a schematic flow diagram of a water treatment system accordingto one embodiment of the invention as discussed in Example 1;

FIG. 4 is a schematic flow diagram of a water treatment system accordingto one embodiment of the invention as discussed in Example 2;

FIG. 5 is a schematic flow diagram of a water treatment system accordingto one embodiment of the invention as discussed in Example 3;

FIGS. 6A-6B are graphs showing water properties measured in the watertreatment system schematically shown in FIG. 5 under an appliedpotential of about 40 volts, wherein FIG. 6A shows the conductivity ofproduct and tank outlet streams and FIG. 6B shows the conductivity of areject stream;

FIGS. 7A-7B are graphs showing water properties measured in the watertreatment system schematically shown in FIG. 5 under an appliedpotential of about 52 volts, wherein FIG. 7A shows the conductivity ofproduct and tank outlet streams and FIG. 7B shows the conductivity of areject stream; and

FIGS. 8A-8B are graphs showing measured water properties of the watertreatment system schematically shown in FIG. 5, wherein FIG. 8A showsthe conductivity of product and tank outlet streams and FIG. 8B showsthe conductivity of a reject stream.

DETAILED DESCRIPTION OF THE INVENTION

United States Patent Applications titled WATER TREATMENT SYSTEM ANDMETHOD by Wilkins et al. and filed on even date herewith; WATERTREATMENT SYSTEM AND METHOD by Jha et al. and filed on even dateherewith; WATER TREATMENT SYSTEM AND METHOD by Ganzi et al. and filed oneven date herewith; WATER TREATMENT SYSTEM AND METHOD by Freydina et al.and filed on even date herewith; WATER TREATMENT SYSTEM AND METHOD byFreydina et al. and filed on even date herewith; WATER TREATMENT SYSTEMAND METHOD by Wilkins et al. and filed on even date herewith; and WATERTREATMENT SYSTEM AND METHOD by Jha et al. and filed on even dateherewith are hereby incorporated by reference herein.

The present invention is directed to a water treatment system and methodfor providing treated water in industrial, commercial and residentialapplications. The treatment system provides treated or softened water toa point of use by removing at least a portion of any hardness-causingspecies contained in water from a water source, such as municipal water,well water, brackish water and water containing foulants. Otherapplications of the system would be in the treatment and processing offoods and beverages, sugars, various industries, such as the chemical,pharmaceutical, food and beverage, wastewater treatments andpower-generating industries.

The water treatment system typically receives water from the watersource or a point-of-entry and treats the water containing at least someundesirable species before delivering the treated water to a point ofuse. A treatment system typically has a reservoir system in line with anelectrodeionization device. The treatment system, in some embodiments,further comprises a sensor for measuring at least one property of thewater or an operating condition of the treatment system. In otherembodiments, the treatment system also includes a controller foradjusting or regulating at least one operating parameter of thetreatment system or a component of the treatment system.

FIG. 1 shows a schematic flow diagram according to one embodiment of awater treatment system. The water treatment system 10 can include areservoir system 12 fluidly connected, typically at an upstream end, toa water source or a point-of-entry 14 and also to an electrodeionizationdevice 16, typically at a downstream end. Water treatment system 10typically includes a point of use 18, which is typically fluidlyconnected downstream of reservoir system 12. In certain embodiments ofthe present invention, water treatment system 10 also has a sensor 20and a controller 22 for controlling or regulating power source 24 whichprovides power to electrodeionization device 16. Electrodeionizationdevice 16 typically removes undesirable species from water to be treatedflowing from point-of-entry 14 to produce treated water for storage intoreservoir system 12 and ultimate delivery to point of use 18.Undesirable species removed by electrodeionization device 16 istypically transferred to an auxiliary use or a drain 26.

Water treatment system 10, in certain embodiments of the invention,further includes pretreatment system 28, which is typically fluidlyconnected upstream of reservoir system 12 or electrodeionization device16. Moreover, water treatment system 10 typically also includes fluidcontrol components, such as pump 30 and valve 32.

The present invention will be further understood in light of thefollowing definitions. As used herein, “pressurized” refers to a systemor component that has a pressure, internal or applied, that is aboveatmospheric pressure. For example, a pressurized reservoir system has aninternal pressure that is greater than atmospheric pressure. Forillustrative purposes, the present invention has been described in termsof an electrodeionization device. However, the systems and techniques ofthe present invention may utilize other electrochemical devices thateffect removal or reduction of an undesirable species from a fluidstream to be treated. For example, the electrochemical device cancomprise an electrodialysis apparatus or, in some embodiments of theinvention, a capacitive deionization apparatus.

FIG. 2 schematically shows a cross-sectional view of fluid and ion flowpaths through one embodiment of an electrodeionization device of thepresent invention. The electrodeionization device or device 16 includesion-depleting or depleting compartments 34 and ion-concentrating orconcentrating compartments 36, positioned between depleting compartments34. Depleting compartments 34 are typically bordered by an anolytecompartment 38 and a catholyte compartment 40. Typically, end blocks(not shown) are positioned adjacent to end plates (not shown) to housean anode 42 and a cathode 44 in their respective compartments. Incertain embodiments of the present invention, the compartments includecation-selective membranes 46 and anion-selective membranes 48, whichare typically peripherally sealed to the periphery of both sides of thecompartments.

The cation-selective membranes and anion-selective membranes aretypically comprised of an ion exchange powder, a polyethylene powderbinder and a glycerin lubricant. In some embodiments of the presentinvention, the cation- and anion-selective membranes are heterogeneouspolyolefin-based membranes, which are typically extruded by athermoplastic process using heat and pressure to create a compositesheet. However, the use of homogeneous membranes alone or in combinationwith heterogeneous membranes is contemplated by the present invention.Representative suitable ion-selective membranes include, for example,web supported using styrene-divinyl benzene with sulphonic acid orquaternary ammonium functional groups, web supported usingstyrene-divinyl benzene in a polyvinylidene fluoride binder, andunsupported-sulfonated styrene and quarternized vinyl benzyl aminegrafts on polyethylene sheet.

Concentrating compartments 36 are typically filled with cation exchangeresin 50 and depleting compartments 34 are typically filled with cationexchange resin 50 and anion exchange resin 52. In some embodiments ofthe invention, the cation exchange and anion exchange resins can bearranged in layers within any of the depleting, concentrating andelectrode compartments so that a number of layers in a variety ofarrangements can be assembled. Other embodiments are believed to bewithin the scope of the invention including, for example, the use ofmixed bed ion exchange resins in any of the depleting, concentrating andelectrode compartments, the use of inert resin between layer beds ofanionic and cationic exchange resins, the use of various types andarrangements of anionic and cationic resins including, but not limitedto, those described by DiMascio et al., in U.S. Pat. No. 5,858,191,which is incorporated herein by reference in its entirety.

In operation, a liquid to be treated 54, typically from an upstreamwater source entering the treatment system at point-of-entry 14, havingdissolved cationic and anionic components, including hardness ionspecies, is introduced into depleting compartments 34 through a manifold60, wherein the cationic components are attracted to the cation exchangeresin 50 and the anionic components are attracted to the anion exchangeresin 52. An electric field applied across electrodeionization device16, through anode 42 and cathode 44, which are typically positioned onopposite ends of electrodeionization device 16, typically passesperpendicularly relative to the fluid flow direction such that cationicand anionic components in the liquid tend to migrate in a directioncorresponding to their attracting electrodes.

Cationic components can migrate through cation-selective membrane 46into adjacent concentrating compartment 36. Anion-selective membrane 48,positioned on the opposite side of concentrating compartment 36, canprevent migration into adjacent compartments, thereby trapping thecationic components in the concentrating compartment. Similarly, anioniccomponents can migrate through the ion-selective membranes, but in adirection that is typically opposite relative to the migration directionof the cationic components. Anionic components can migrate throughanion-selective membrane 48, from depleting compartment 34, intoadjacent concentrating compartment 36. Cation-selective membrane 46,positioned on the other side of concentrating compartment 36, canprevent further migration, thus trapping anionic components in theconcentrating compartment. In net effect, ionic components are removedor depleted from the liquid 54 in depleting compartments 34 andcollected in concentrating compartments 36 resulting in a treated waterproduct stream 56 and a concentrate or waste stream 58.

In some embodiments of the present invention, the applied electric fieldacross electrodeionization device 16 can create a polarizationphenomenon, which leads to the dissociation of water into hydrogen andhydroxyl ions. The hydrogen and hydroxyl ions can regenerate the ionexchange resins 50 and 52 in depleting compartments 34, so that removalof dissolved ionic components can occur continuously and without aseparate step for regenerating exhausted ion exchange resins because ofthe ionic species migration. The applied electric field acrosselectrodeionization device 16 is typically a direct current. However,any applied electric field that creates a bias or a potential differencebetween one electrode and another can be used to promote migration ofionic species. Therefore, an alternating current may be used, providedthat there is a potential difference between electrodes that issufficient to attract cationic and anionic species to the respectiveattracting electrodes. In yet another embodiment of the invention, analternating current may be rectified, for example, by using a diode or abridge rectifier, to convert an alternating current to a pulsatingdirect current such that, when the current is applied across theelectrodeionization device, a potential gradient is created thatattracts the respective ionic species.

The electroactive media, for example, the ion exchange resin beads 50and 52, typically utilized in depleting compartments 34, can have avariety of functional groups on their surface regions, such as tertiary,alkyl amino groups and dimethyl ethanolamine. These materials can alsobe used in combinations with ion exchange resin materials having variousfunctional groups on their surface regions, such as quaternary ammoniumgroups.

Reservoir system 12 can store or accumulate water from point-of-entry 14or a water source and may also serve to store softened or treated waterfrom product stream 56 from electrodeionization device 16 and alsoprovide water, typically treated water or treated water mixed with waterfrom point-of-entry 14 to point of use 18 through a distribution system.In one embodiment of the present invention, reservoir system 12 is apressurized reservoir system. Pressure in the pressurized reservoirsystem can be created by various methods and techniques, for example, bypressurizing the water with a pump or by elevating the water source,thus creating head pressure.

In some embodiments of the present invention, reservoir system 12comprises a pressurized vessel or a vessel that has inlets and outletsfor fluid flow such as an inlet 62 and an outlet 64. Inlet 62 istypically fluidly connected to point-of-entry 14 and outlet 64 istypically fluidly connected to a water distribution system or to pointof use 18. Reservoir system 12 can have several vessels or vesselshaving several inlets positioned at various locations on each vessel.Similarly, outlet 64 may be positioned on each vessel at variouslocations depending on, among other things, demand or flow rate to pointof use 18, capacity or efficiency of electrodeionization device 16 andcapacity or hold-up of reservoir system 12. Reservoir system 12 mayfurther comprise various components or elements that perform desirablefunctions or avoid undesirable consequences. For example, reservoirsystem 12 can have vessels having internal components, such as bafflesthat are positioned to disrupt any internal flow currents within thevessels of reservoir system 12. In some embodiments of the invention,reservoir system 12 has a heat exchanger for heating or cooling thefluid. For example, reservoir system 12 may comprise a vessel with aheating coil, which can have a heating fluid at an elevated temperature.The heating fluid may be hot water in closed-loop flow with a heatingunit operation such as a furnace so that when the heating fluidtemperature is raised in the furnace, the temperature of the water inthe vessel increases through heat transfer. Other examples of auxiliaryor additional components include, but are not limited to, pressurerelief valves designed to relieve internal pressure of any vessels andavoid or at least reduce the likelihood of vessel rupture and thermalexpansion tanks that are suitable for maintaining a desired operatingpressure. The size and capacity of a thermal expansion tank will dependon factors including, but not limited to, the total volume of water, theoperating temperature and pressure of the reservoir system.

In operation, reservoir system 12 is typically connected downstream ofpoint-of-entry 14 and fluidly connected in-line, such as in arecirculation loop, with electrodeionization device 16. For example,water from point-of-entry 14 can flow into inlet 62 and can mix with thebulk water contained within reservoir system 12. Water can exitreservoir system 12, typically through outlet 64, and directed to pointof use 18 or through pump 30 into electrodeionization device 16 fortreatment or removal of any undesirable species. Treated water leavingelectrodeionization device 16 may mix with water from point-of-entry 14and enter reservoir system 12 through inlet 62. In this way, a loop canbe defined or formed between reservoir system 12 and electrodeionizationdevice 16 and feedwater from point-of-entry 14 can replenish waterdemand created by and flowing to point of use 18.

Point-of-entry 14 can provide water from a water source or connects thewater source to the water treatment system. The water source may be apotable water source, such as municipal water or well water or it may bea non-potable, such as a brackish or salt-water source. Typically, anintermediate treatment or treatment system treats the water so that issuitable for human consumption before reaching point-of-entry 14. Thewater typically contains dissolved salts or ionic or ionizable speciesincluding sodium, chloride, calcium ions, magnesium ions, carbonates,sulfates or other insoluble or semi-soluble species or dissolved gases,such as silica and carbon dioxide. Moreover, the water may containadditives, such as but not limited to fluoride, chlorate and bromate.

In another embodiment of the present invention, water treatment system10 includes to a water distribution system, which in turn connects to apoint of use. The water distribution system may comprise components thatare fluidly connected to provide pressurized water, typically treatedwater, from reservoir system 12 to point of use 18. The waterdistribution system may comprise an arrangement of pipes, valves, tees,pumps and manifolds to provide water from reservoir system 12 to one orseveral points of use 18 or to any component of water treatment system10.

Point-of-use 18 is typically any device or appliance that requires ordemands water. For example, point of use 18 may be an appliance, such asa washing machine or a dishwasher, or may be a faucet serving to providewater to a kitchen sink or a showerhead. In another embodiment of theinvention, point of use 18 comprises a system for providing watersuitable for household or residential use. In still another embodimentof the invention, water treatment system 10 also comprises a sensor,typically a water property sensor, which measures at least one physicalproperty of the water in water treatment system 10. For example, sensor20 may be a device that can measure turbidity, alkalinity, waterconductivity, pH, temperature, pressure or flow rate. Sensor 20 may beinstalled or positioned within water treatment system 10 to measure aparticularly preferred water property. For example, sensor 20 may be awater conductivity sensor installed in reservoir system 12 so thatsensor 20 measures the conductivity of the water, which indirectlymeasures the quality of the water available for service in point of use18. In another embodiment of the invention, sensor 20 may comprise aseries or a set of sensors in reservoir system 12. The set of sensorsmay be arranged and connected to controller 22 so that the quality ofwater in reservoir system 12 is monitored, intermittently orcontinuously through controller 22, and the quality of water or theoperation of electrodeionization device 16 can be optimized as describedbelow. Other embodiments may comprise a combination of sets of sensorsin various locations throughout water treatment system 10. For example,sensor 20 may be a flow sensor measuring a flow rate to a point of use18 and further include any of a nephelometer, pH, temperature andpressure sensor monitoring the operating condition of water treatmentsystem 10.

In accordance with another embodiment of the present invention, watertreatment system 10 further comprises a pretreatment system 28 designedto remove a portion of any undesirable species from the water before thewater is introduced to, for example, reservoir system 12 orelectrodeionization device 16. Examples of pretreatment systems include,but are not limited to, reverse osmosis devices, which are typicallyused to desalinate brackish or salt water. Carbon or charcoal filters,as components of pretreatment systems, may be necessary to remove atleast a portion of any chlorine, including active chlorine or anyspecies that may foul or interfere with the operation ofelectrodeionization device 16.

Pretreatment system 28 may be positioned anywhere within water treatmentsystem 10. For example, pretreatment system 28 may be positionedupstream of reservoir system 12 or downstream of pressurized system 12but upstream of electrodeionization device 16 so that at least somechlorine species are retained in reservoir system 12 but are removedbefore the water enters electrodeionization device 16.

In accordance with one or more embodiments of the present invention,water treatment system 10 further comprises a controller 22 that iscapable of monitoring and regulating the operating conditions of watertreatment system 10 and its components. Controller 22 typicallycomprises a microprocessor-based device, such as a programmable logiccontroller (PLC) or a distributed control system that receives or sendsinput and output signals to components of water treatment system 10. Forexample, controller 22 may be a PLC that can send a signal to powersource 24, which can supply power to electrodeionization device 16 ormay provide a signal to a motor control center that provides power topumps 30. In certain embodiments, controller 22 can regulate theoperating conditions of water treatment system 10 in open-loop orclosed-loop control scheme. For example, controller 22, in open-loopcontrol, may provide signals to the water treatment system such thatwater is treated without measuring any operating condition. In contrast,controller 22 may control the operating conditions in closed-loopcontrol so that operating parameters may be adjusted depending on ameasured operating condition. In yet another embodiment of theinvention, controller 22 may further comprise a communication systemsuch as a remote communication device for transmitting or sending any ofmeasured operating condition or operating parameter to a remote station.

In accordance with another embodiment of the present invention,controller 22 may provide a signal that actuates any valves 32 in watertreatment system 10 so that fluid flow parameters in water treatmentsystem 10 can be adjusted or adjustable based on a variety of operatingparameters including, but not limited to, the quality of water frompoint-of-entry 14, the quality of water to point of use 18, the demandor quantity of water to point of use 18, the operating efficiency orcapacity of electrodeionization device 16, or any of a variety ofoperating conditions, such as the water conductivity, pH, temperature,pressure, composition and flow rate. In accordance with one embodimentof the invention, controller 22 can receive signals from sensor 20 sothat controller 22 can be capable of monitoring the operating parametersof water treatment system 10. For example, sensor 20 may be a waterconductivity sensor positioned within reservoir system 12 so that thewater conductivity in reservoir system 12 is monitored by controller 22.Controller 22 can, based on the water quality measured by sensor 20,control power source 24, which provides an electric field toelectrodeionization device 16. In operation, controller 22 can increase,decrease or otherwise adjust the voltage, current, or both, supplied toelectrodeionization device 16.

In accordance with another embodiment of the present invention,controller 22 may reverse the direction of the applied field from powersource 24 to electrodeionization device 16 according to a predeterminedschedule or according to an operating condition, such as the waterquality or any other operating parameter. Polarity reversal, which hasbeen described by, for example, Giuffrida et al., in U.S. Pat. No.4,956,071, and which is incorporated herein by reference in itsentirety, is considered to be within the scope of the present invention.

Controller 22 may be configured or configurable by programming or may beself-adjusting such that it is capable of maximizing any of the servicelife and the efficiency of or reducing the operating cost of treatmentsystem 10. For example, controller 22 may comprise a microprocessorhaving user-selectable set points or self-adjusting set points thatadjusts the applied voltage and current to electrodeionization device16, the flow rate through the concentrating and depleting compartmentsof the electrodeionization device or the flow rate to discharge to drain26 from the electrodeionization device or the pretreatment system orboth. In another embodiment of the invention, controller 22 may beprogrammed to be capable of adjusting a change in cycle ofelectrodeionization device. For example, controller 22 may control theperiod between plurality reversal of an applied electric field acrossthe electrodeionization device based on a measured water property suchas, but not limited to, the conductivity of the water being delivered tothe point of use. In another embodiment of the invention, controller 22can calculate a Langelier Saturation Index (LSI) of the water inreservoir system 12 and adjust an operating parameter of the system 10based on the difference between the calculated LSI and a set point. LSIcan be calculated according to, for example, the procedure described inASTM D 3739. In some embodiments of the invention, the treated fluid,such as the softened water, has a low LSI so that it has a low tendencyto scale. As used herein, low LSI water has a LSI of about less than 2,preferably, less than about 1, and more preferably, less than aboutzero. In some embodiments, the present invention provides treatedliquids, such as water, having a low conductivity. As used herein, a lowconductivity liquid has a conductivity of less than about 300 μS/cm,preferably less than about 220 μS/cm and more preferably, less thanabout 200 μS/cm.

Controller 22 can incorporate dead band control to reduce the likelihoodof unstable on/off control or chattering. Dead band refers to the rangeof signal outputs that a sensor provides without necessarily triggeringa responsive control signal. The dead band may reside, in someembodiments, intrinsically in one or more components of the treatmentsystem, such as the sensor, or may be programmed as part of the controlsystem, or both. Dead band control can avoid unnecessary intermittentoperation by smoothing out measurement excursions. Such controltechniques can prolong the operating life or mean time before failure ofthe components of treatment system 10. Other techniques that can be usedinclude the use of voting, time-smoothing or time-averaging measurementsor combinations thereof.

Accordingly, in accordance with one or more embodiments of the presentinvention, the treatment system stores water from point-of-entry 14,which is typically connected to a water source, at a pressure aboveatmospheric pressure in a first zone of reservoir system 12. Reservoirsystem 12 can be fluidly connected to a water distribution system thattransfers treated water to point of use 18. Treatment system 18 can alsohave an electrodeionization device 16 that treats water frompoint-of-entry 14 by removing at least a portion of any undesirablespecies to produce treated water that is introduced into reservoirsystem 12 in a second zone of reservoir system 12. First and secondzones of reservoir system 12 can be monitored by at least one waterquality sensor, more preferably, a set of water quality sensorsconnected to controller 22, which, in turn, can adjust an operatingparameter of electrodeionization device 16. In this way, controller 22can monitor the first and second zones of reservoir system 12 andregulate the operation of electrodeionization device 16 depending on anyof the properties measured by a sensor or a set of sensors 20 whichmeasures the water properties of the water in the first and secondzones.

In yet another embodiment of the present invention, controller 22,through sensor or set of sensors 20, can measure a water property of thewater in the first and second zones of reservoir system 12 and can alsomeasure a flow rate flowing into at least one point of use 18 and canadjust an operating parameter of electrodeionization device 16 based onthe measured properties. For example, when an increased flow rate ismeasured to point of use 18, controller 22 adjusts an operatingparameter of electrodeionization device 16 to treat water to compensatefor additional demand flowing into point of use 18. In another example,controller 22 can adjust an operating parameter of electrodeionizationdevice 16 depending on the volume in the first and second zones ofreservoir system 12 and the historical demand required by point of use18.

In accordance with another embodiment of the present invention,controller 22 regulates the operation of the treatment system byincorporating adaptive or predictive algorithms, which are capable ofmonitoring demand and water quality and adjusting the operation of theelectrodeionization device, such as increasing or decreasing the appliedvoltage or the period between electric field reversals ofelectrodeionization device 16. For example, controller 22 may utilizepredictive techniques in anticipating higher demand for treated waterduring early morning hours in a residential application to supply pointof use 18 serving as a showerhead.

In another embodiment of the present invention, treatment system 10comprises a flow regulator 32 a for regulating the flow of a dischargeor waste stream to drain 26. Flow regulator 32 a can adjust the amountor volume of the waste stream that flows to drain 26. In another aspectof the embodiment, flow regulator 32 a is capable of creating apulsating flow to drain 26 and can comprise any of a valve or an orificeplate or a combination thereof. In another embodiment of the invention,because flow regulator 32 a is typically fluidly disposed downstream inthe treatment system, the pulsating flow can create a pressure wave orfront that can propagate throughout or a portion of the treatment system10. In another aspect of one embodiment, the pressure wave is sufficientto dislodge any solids, precipitated material or gases trapped oraccumulated in treatment system 10 so that the material or gas can becarried through and discharged to drain 26 or released through a vent(not shown) of treatment system 10.

According to another embodiment of the present invention, the flowregulator is a valve that can be intermittently opened and closedaccording to a predetermined schedule for a predetermined period of timeto allow a predetermined volume to flow. The amount or volume of fluidflowing to drain can be adjusted or changed by, for example, changingthe frequency the flow regulator is opened and closed or by changing theduration during which the flow regulator is open or closed. In oneembodiment, the flow regulator can be controlled or regulated bycontroller 22 through, for example, an actuation signal. Thus, in oneembodiment of the invention, controller 22 provides an actuation signal,such as a radio, current or a pneumatic signal, to an actuator, with,for example, a motor or diaphragm, that opens and closes the flowregulator.

The fluid regulated by valve or flow regulator 32 a can be any fluid inany stream to be discharged to waste such as waste stream 58 or a wastestream from a pretreatment device. Thus, in one embodiment, if thetreatment system comprises a pretreatment system with a reverse osmosisapparatus, then the waste stream can include the discharge fluid fromthe electrodeionization device and the discharge fluid from the reverseosmosis apparatus. In yet another aspect of the present invention, withreference to FIG. 2, waste stream 58 can include any of the fluid fromelectrode compartments 38 and 40 or concentrating compartment 36 of theelectrodeionization device. It can be seen that the fluid from electrodecompartments or the concentrating compartments may be directly sent todrain 26 or may be recirculated, before discharge, to the electrodecompartments, the concentrating compartment or both. In this way, theoverall efficiency of the treatment system can be increased whiledecreasing operating costs because of less total discharge. In yetanother embodiment, the present invention provides for adjusting anoperating parameter, for example, the rate of discharge to drain or theperiod during discharge, as a function of at least one measuredparameter such as the system operating pressure. For example, the periodduring which valve 321, in FIG. 3, is actuated open to discharge can beadjusted based on the measured pressure of the liquid supplied to pointof use 18. In some cases, the flow regulator may be actuated open toreduce the measured pressure or it may be actuated to a minimum,depending on the type of valve, when the measured pressure is below apredetermined value. Such a secondary control scheme can be incorporatedor nested within any of the existing control loops actuating the flowregulator.

In accordance with one or more embodiments of the present invention, theflow regulator comprises a valve that is a fast-opening valve withminimal or no pressure drop therethrough. Examples of suitable valvesinclude, but are limited to, diaphragm valves as well as ball, gate andbutterfly valves, which are available from, for example, Bürkert USA(Irvine, Calif.) and South Bend Controls, Inc. (South Bend, Ind.). Othervalves that can be used include pinch or flex valves or any valve thatcan shed or dislodge any precipitated scales during activation.

In another embodiment of the present invention, the flow regulator canserve as part of a pressure control loop as well as in part of aconcentrate discharge control loop. For example, the flow regulator canbe actuated by controller 22 when the measured conductivity of theconcentrate stream reaches the set point. A separate pressure controlloop can be juxtaposed to relieve pressure in system 10. In any of theabove-mentioned control schemes, the control loops can incorporatefeedback as well as any of proportional, derivative, integral or,preferably, a combination thereof.

In another embodiment, the flow regulator can have an applied electricalcharge flowing therethrough. The applied charge is, in one embodiment, avoltage or a current that is sufficient to generate ionic species aroundthe flow regulator. And, in a preferred embodiment, the applied chargeis sufficient to generate positively-charged ionic species. In yetanother embodiment, the applied charge creates ionic species that lowersthe pH of the fluid surrounding the flow regulator. Thus, in one aspectof one embodiment, the applied charge is sufficient to generatepositively-charged hydrogen ions. Preferably, the applied chargegenerates sufficient hydrogen ions that, in effect, changes the pH toless than about 7, preferably, to less than about 6, and morepreferably, to less than about 5. Thus, according another aspect of oneembodiment of the present invention, the flow regulator is any of avalve or a plate with a flow orifice or a combination thereof that canhave an applied charge that generates sufficient ionic species to reducethe pH of the surrounding fluid. The flow regulator can be made from anysuitable material that can tolerate prolonged water exposure. Examplesof such materials include, but are not limited to, stainless steels,plastics, conductive composites like graphite.

In yet another aspect of one embodiment of the present invention, thecharge is applied periodically or applied depending an operatingcondition of the treatment system. For example, the charge can beapplied charge can be applied according to a predetermined periodicschedule or, the applied charge can be applied when an operatingparameter, such as any of the water conductivity, the pressure dropacross the electrodeionization device, the water pH, the change voltageor current on the electrodeionization device or any combination thereof.

In another embodiment of the present invention, water, typical fromwaste stream 58, to auxiliary use can serve or provide additional orsecondary benefits. For example, waste stream 58, rather than going todrain 26, may be used to provide irrigating water to any residential,commercial or industrial use, such as for irrigating, for recycling orfor recovery of collected or concentrated salts.

The present invention will be further illustrated through the followingexamples, which are illustrative in nature and is not intended to limitthe scope of the invention.

EXAMPLE 1

A treatment system, schematically shown in FIG. 3, was designed andevaluated for performance. The treatment system 10 had anelectrodeionization device 16 with a pretreatment system (not shown) anda pressurized vessel 12. Water, from point-of-entry 14, was introducedinto pressurized vessel 12 and was re-circulated throughelectrodeionization device 16. The water treatment system was controlledby a programmable controller (not shown) based on the measured waterconductivity, as measured by sensors 20 b and 20 c, upstream of an inlet62 and downstream of an outlet 64 of pressurized vessel 12.

Electrodeionization device 16 comprised a 10-cell pair stack with13-inch flowpaths. Each cell was filled with AMBERLITE® SF 120 resin andAMBERLITE® IRA 458 resin, both available from Rohm & Haas Company,Philadelphia, Pa. The electrodeionization device utilized an expandedtitanium electrode coated with ruthenium oxide.

Pressurized vessel 12 was a 10-inch diameter fiberglass vessel withabout a 17-gallon capacity. The concentrate stream leaving theelectrodeionization device was partially re-circulated and partiallyrejected to a drain 26 by regulating valves 32 b, 32 c, 32 e, 32 f, 32g, 32 h, 32 j and 321. Make-up water, from point-of-entry 14, was fedinto the recirculating stream to compensate for water rejected to drain26 by regulating valves 32 b, 32 c and 32 d in proper sequence.

The treated water exiting electrodeionization device 16 was transferredto vessel 12 by actuating valves 32 i and 32 k. The flow rate of treatedwater to a point of use 18 from outlet 64 of pressurized vessel 12 wasregulated by adjusting valve 32 a. Several sensors measuring operatingconditions and water properties were installed throughout the watertreatment system 10 including pressure indicators 20 d, 20 f, 20 g, 20 hand 20 i, flow rate indicators 20 a, 20 e, 20 j and 20 k andconductivity sensors 20 b, 20 c and 20 l.

The controller comprised a MicroLogix™ 1000 programmable controller,available from Allen-Bradley Company, Inc., Milwaukee, Wis. Theelectrodeionization device was set to start up by a flow switch signalor when the water conductivity of the outlet stream leaving thepressurized vessel was detected to be higher than a set point. The feedto the electrodeionization device was circulated from the pressurizedvessel via a second feed pump. The polarity of the electric fieldapplied to the electrodeionization device was reversed as necessary.

Valves 32 j and 32 l was an “on-off” type valve that provided a fullyopen or a fully closed flow path to drain 26. Valves 32 j and 32 lcomprised of a needle valve or a ball valve. Valves 32 j and 32 l wasactuated by a controller (not shown) and opened and closed according toa predetermined schedule. In addition, valves 32 j and 32 l had anapplied positive charge that was sufficient to produce hydrogen ions tolower the pH of the surrounding fluid.

EXAMPLE 2

An in-line water treatment system, schematically shown in FIG. 4, wasdesigned, operated and evaluated for performance. The water treatmentsystem 10 had an electrodeionization device 16 and a pressurized storagevessel 12. Water, from point-of-entry 14, was introduced intopressurized storage vessel 12 through inlet 62 and was circulated usingpumps 30 a and 30 b and treated through pretreatment units 28 a and 28 band electrodeionization device 16. The water treatment system wascontrolled by a programmable controller (not shown) based on themeasured water conductivity, as measured by sensors any of 20 a, 20 band 20 c.

Electrodeionization device 16 was comprised of a 10-cell pair stack withflowpaths that were about 7.5-inches long and about 2.5-inches wide.Each cell was filled with about 40% AMBERLITE® SF 120 resin and about60% AMBERLITE® IRA 458 resin, both available from Rohm & Haas Company,Philadelphia, Pa. The electrodeionization device had an expandedtitanium electrode coated with ruthenium oxide.

The controller was a MICROLOGIX™ 1000 programmable controller availablefrom Allen-Bradley Company, Inc., Milwaukee, Wis. Theelectrodeionization device was set to start up by a flow switch signalor when the water conductivity of the outlet stream leaving thepressurized vessel was higher than a set point. The electrodeionizationdevice operated until the conductivity reached the set point. The feedfrom the electrodeionization device was circulated from the pressurizedvessel via a second feed pump. The polarity of the electric fieldapplied to the electrodeionization device was reversed about every 15minutes. In addition to controlling the components ofelectrodeionization device 16, the PLC collected, stored and transmittedmeasured data from sensors 20 a, 20 b, 20 c and 20 d.

Pressurized vessel 12 was a 10-inch diameter fiberglass vessel withabout a 30-gallon capacity. Pressurized vessel 12 was fitted with avalve head and a center manifold pipe. The concentrate stream leavingthe electrodeionization device was partially circulated and partiallyrejected to a drain 26 by regulating valves 32 c, 32 d, 32 e, 32 f and32 g. Make-up water, from point-of-entry 14, was fed into thecirculating stream to compensate for any water that was rejected todrain 26.

The pretreatment system comprised of an aeration iron-filter with a25-micron rating, a 20-inch×4-inch sediment filter and a 20-inch×4-inchcarbon block filter.

In the one flow direction, water from pressure vessel 12 was pumped bypump 30 a, from pressure vessel 12 through valve 32 c, to pretreatmentunit 28 a before being introduced to the depleting compartments (notshown) of electrodeionization device 16. Treated water fromelectrodeionization device 16 was directed by valve 32 f to storage inpressure vessel 12. Fluid collecting removed ionic species wascirculated by pump 30 b through pretreatment unit 28 b, theconcentrating and electrode compartments (not shown) ofelectrodeionization device 16 and valve 32 e. When the direction of theapplied electric field was reversed, the flow directions werecorrespondingly adjusted so that pump 30 a, pretreatment unit 28 a, andvalves 32 c and 32 f circulated the fluid, which was accumulating ionicspecies, while flowing through the concentrating and electrodecompartments of electrodeionization device 16. Similarly, water to betreated was pumped from pressure vessel 12 using pump 30 b through valve32 d to pretreatment unit 28 b before being introduced and treated inthe depleting compartments of electrodeionization device 16. Treatedwater was directed by valve 32 e to pressure vessel 12.

The flow rate of treated water, as measured by flow indicator 20 d, to apoint of use 18 from outlet 64 of pressurized vessel 12 was regulated byadjusting valves 32 a and 32 b. To discharge concentrate or wastestream, valve 32 g was operated as necessary. Water from point-of-entry14 was used to restore and replace fluid that was discharged to drain26. Valve 32 g was a diaphragm valve.

The water treatment system was operated until a target set point ofabout 220 μS/cm was reached and stable for about one minute. The appliedvoltage to the electrodeionization device was about 46 volts. The flowrates into the depleting and concentrating compartments were maintainedat about 4.4 liters per minute. The reject flow rate was controlled todischarge about 270 ml every about 30 seconds. The pressure in thevessel was about 15 psig to about 20 psig. Discharge valve 32 g wasdisassembled after the run and was found to have minimal scaling.

EXAMPLE 3

An in-line water treatment system, schematically shown in FIG. 5, wasdesign operated and evaluated for performance. The water treatmentsystem 10 had an electrodeionization device 16 and a vessel 12. Waterfrom point-of-entry 14 was introduced into pressure vessel 12 throughinlet 62. Water to be treated was withdrawn from pressurized storagevessel 12 and introduced into electrodeionization device 16 througheither of valves 32 a or 32 b. The water treatment system also hadpretreatment systems 28 a and 28 b upstream of electrodeionizationdevice 16. Streams exiting electrodeionization device 16 was transferredthrough pumps 30 a and 30 b into either of pressurized storage vessel 12or circulated back into electrodeionization device 16, depending on theservice of valves 32 c and 32 d. Discharge to drain 26 of a concentratestream was controlled by actuating valve 32 e. Treated water waswithdrawn from pressurized storage vessel 12 through outlet 64 andintroduced as the product point of use 18. The water treatment systemwas controlled by a programmable controller (not shown) based on themeasured water conductivity. The water treatment system was operateduntil a conductivity of about 220 μS/cm was achieved. Treated water fromthe water treatment system was withdrawn from pressurized storage vessel12 and delivered to point of use 18 at a rate of between about 11 toabout 14 gallons about every 3 hours. The flow rate through pumps 30 aand 30 b was monitored through flow meters 20 a and 20 b, respectively.

Electrodeionization device 16 was comprised of a 25 cell pair stackbetween expanded mesh ruthenium oxide electrodes. Electrodeionizationdevice 16 was configured so that treated water or product flowed fromthe depleting compartments to the cathode compartments and theconcentrate stream from the concentrating compartments circulatedthrough the anode compartment. Each cell of the electrodeionizationdevice was filled with about 40% AMBERLITE® SF 120 resin and about 60%AMBERLITE® IRA 458 resin, both available from Rohm & Haas Company,Philadelphia, Pa.

The programmable controller was a MICROLOGIX™ and 1000 programmablecontroller available from Allen-Bradley Company, Inc., Milwaukee, Wis.

An electric field was applied across the electrodeionization device andwas reversed about every 15 minutes. The applied electric field acrosselectrodeionization device 16 was initially operated at about 40 V andwas changed to about 52 V.

Vessel 12 was about a 10-inch diameter fiberglass tank containing about17 gallons. The feed pressure from point-of-entry 14 was about 30 psig.Flow rates in the diluting and concentrating streams was maintained atabout 1.3 to about 1.4 liters per minute.

Pretreatment systems 28 a and 28 b was comprised of 5-inch carbon blockfilters with about a 0.5 micron rating. Additionally, a pretreatmentsystem comprised of one depth filter and one 1-inch sediment filter wasused to remove heavy particulates before introducing the water to betreated in vessel 12.

In one liquid circuit, water from vessel 12 was introduced through valve32 a into electrodeionization device 16 where it was treated. Thetreated water was returned to vessel 12 through pump 30 a and valve 32c. In another liquid circuit, a concentrating stream flowing in aconcentrating compartment of electrodeionization device 16 wascirculated through pump 30 b and directed by valves 32 d and 32 b. Inanother liquid circuit, water to be treated was withdrawn from outlet 64of vessel 12 and introduced into a second depleting compartment ofelectrodeionization device 16 through valve 32 b. The treated waterexiting electrodeionization device 16 was then transferred back intovessel 12 by pump 30 b and valve 32 c. A fourth liquid circuit,comprising a concentrating stream from a second concentratingcompartment of electrodeionization device 16, was circulated byoperating pump 30 a and directing the flow through valve 32 c, 32 d and32 a.

The water treatment system was operated under varying conditions and theoperating parameters were measured and illustrated on FIGS. 6A, 6B, 7A,7B, 8A and 8B. In each of the figures, an operating parameter was variedto evaluate the efficiency and performance of the water treatmentsystem.

The water treatment system was operated so that an intermittent flushingor discharge of the concentrate stream to drain 26 occurred for about 6seconds every 24 seconds. The volume discharged to drain was about 300milliliters per minute. Product water was withdrawn from vessel 12 at arate of about 12.5 gallons every three hours. At an applied electricpotential of about 40 V, the electrodeionization device automaticallyshut down, after reaching the set point, and remained shut down for 25minutes before the next product withdrawal, to point of use 18. Theduration of the shutdown time represents the efficiency of the system inoperation. FIGS. 6A and 6B show that under an applied potential of about40 V, the water treatment system can be operated to produce softenedwater having a conductivity of about 220 μS/cm and a reject to draincycle that drains intermittently.

FIGS. 7A and 7B show operating data of the water treatment systemoperated under a higher potential of about 52 V and with a decreasedflushing cycle of about 4 seconds about every 26 seconds. Duringoperation, the electrodeionization device had a shutdown period of about57 minutes. Product water was withdrawn from vessel 12 at a rate ofabout 11.7 gallons every about three hours. FIGS. 7A and 7B show thatthe water treatment system can be operated to produce treated water witha decrease in the amount of flushing time without a decrease inperformance and water quality. Also, as shown in FIG. 7B and compared toFIG. 6B, the conductivity of the reject stream increased at the sametime the duration of shutdown increased. Thus, FIGS. 7A and 7B show thatthe water treatment system can be operated to produce treated water at ahigher efficiency as compared to the operating conditions associatedwith FIGS. 6A and 6B.

FIGS. 8A and 8B show the influence of an increased load on the watertreatment system. The volume of the product to point of use 18 wasincreased to about 14 gallons every three hours. Under these operatingconditions, the duration of shutdown time of the electrodeionizationdevice decreased to about 30 minutes, as expected, because of theincreased load. FIGS. 8A and 8B show that the system can still beoperated with an increased load.

Those skilled in the art would readily appreciate that all parametersand configurations described herein are meant to be exemplary and thatactual parameters and configurations will depend upon the specificapplication for which the systems and methods of the present inventionare used. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific embodiments of the invention described herein. Forexample, those skilled in the art can recognize that the presentinvention can be configured so that the electrodeionization device canbe installed within the reservoir system when it is desirable to do sosuch as when installation space or volume is limited by existingequipment or structure or that a time delay can be used so that theelectrodeionization device would be flushed for a predetermined periodafter shutdown. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto, the invention maybe practiced otherwise than as specifically described. The presentinvention is directed to each individual feature, system, or methoddescribed herein. In addition, any combination of two or more suchfeatures, systems or methods, if such features, systems or methods arenot mutually inconsistent, is included within the scope of the presentinvention. The present invention has been described using water as thefluid but should not be limited as such. For example, where reference ismade to treated water, it is believed that other fluids that can betreated according to the present invention. Moreover, where reference ismade to a component of the system, or to a step of the method, of thepresent invention that adjusts, modifies, measures or operates on wateror water property, the present invention is believed to be applicable aswell. Thus, the fluid to be treated may be a fluid that is a mixturecomprising water. Accordingly, the fluid can be a liquid that compriseswater.

1. An electrochemical device comprising: an anode compartment and acathode compartment; a depleting compartment in ionic communication withat least one of the anode compartment and the cathode compartment; aconcentrating compartment in ionic communication with the depletingcompartment; and a positively-charged flow regulator comprising a floworifice positioned downstream of the concentrating compartment.
 2. Thedevice of claim 1 further comprising a power source for applying apositive electrical charge to the positively-charged flow regulatoraccording to a predetermined charge schedule.
 3. The device of claim 1wherein the positively-charged flow regulator comprises a valve.
 4. Thedevice of claim 1 wherein the positively-charged flow regulatorcomprises a graphite material.
 5. The device of claim 1 wherein thepositively-charged flow regulator comprises a diaphragm valve.
 6. Asystem comprising: a point-of-entry; an electrodeionization devicecomprising a depleting compartment and a concentrating compartment,fluidly connected to the point-of-entry; a flow regulator fluidlyconnected downstream of the concentrating compartment; a power sourceoperatively configured to provide an applied positive electrical chargeon the flow regulator, and to provide an electric current through theelectrodeionization device; a controller operatively coupled to thepower source, and configured to regulate the applied positive electricalcharge on the flow regulator according to a predetermined schedule, andfurther configured to reverse a polarity of the electric current throughthe electrodeionization device; a reservoir system fluidly connected tothe depleting compartment; and a point of use fluidly connected to thereservoir system.
 7. The system of claim 6 wherein the flow regulatorcomprises a valve.
 8. The system of claim 6 wherein the controller isoperatively coupled to the flow regulator, and configured to regulatethe flow regulator to discharge a predetermined volume of a fluidaccording to a predetermined discharge schedule.
 9. The system of claim6 wherein the flow regulator comprises a plate having a flow orifice.10. The system of claim 6 wherein the reservoir system has a pressurethat is above atmospheric pressure.
 11. The system of claim 6 whereinthe point of use comprises a household appliance.
 12. Anelectrodeionization device comprising: a cathode compartment and ananode compartment; a concentrating compartment fluidly connectedupstream of the anode compartment; a depleting compartment in ioniccommunication with the concentrating compartment, and fluidly connectedto the cathode compartment; and a flow regulator regulated by acontroller according to a predetermined discharge schedule and fluidlyconnected downstream of the concentrating compartment for regulating aflow of a waste stream to a drain, the flow regulator has an appliedpositive charge.
 13. The device of claim 12 wherein the flow regulatorcomprises a valve.
 14. The device of claim 12 further comprising anelectric power source configured to apply the positive charge on theflow regulator.
 15. The device of claim 14 wherein the controller isconfigured to regulate the electric power source applying the positivecharge according to a predetermined charge schedule.
 16. A method ofsoftening water comprising: introducing water to a depleting compartmentof an electrochemical device to produce softened water; recirculating aconcentrating stream in a concentrating compartment of theelectrochemical device; and changing a pH of the concentrating streamproximate a flow regulator by applying an electrical charge on the flowregulator.
 17. The method of claim 16 wherein changing the pH of theconcentrating stream changes the pH to less than about
 7. 18. The methodof claim 16 wherein the electrical charge is applied according to apredetermined charge schedule.
 19. The method of claim 18 furthercomprising measuring a property of the softened water.
 20. The method ofclaim 19 wherein adjusting the pH comprises generating hydrogen ions.21. The method of claim 19 wherein adjusting the pH comprises applyingthe electrical charge on the flow regulator according to a chargeschedule.
 22. The method of claim 21 further comprising adjusting thecharge schedule based on the softened water property.
 23. Anelectrodeionization device comprising: a concentrating compartment witha flowing waste stream; means for discharging a portion of the wastestream from the concentrating compartment to a drain according to apredetermined schedule; and means for generating hydrogen ions in afluid flowing through said discharging means.
 24. Theelectrodeionization device of claim 23 further comprising means foradjusting the predetermined schedule.
 25. An electrodeionization devicecomprising: a concentrating compartment with a waste stream, and havingion exchange media therein; means for discharging the waste stream to adrain according to a predetermined discharge schedule; and means forapplying a positive charge on the means for discharging the wastestream.